A. Technical Field
The present invention relates to an embossed crepe paper excellent in a fluffy feel and its manufacturing method. In detail, the present invention is designed for: a fluffy-feel-abundant crepe paper utilized for such as facial tissues by embossing a raw crepe paper; and a method for manufacturing such a crepe paper.
B. Background Art
Among other tissue products used for such as cosmetic uses, there are two- or three-ply ones made of thin crepe paper. Among others such as toilet paper products, there are those which are provided with properties such as bulkiness and softness by embossment of crepe papers.
Separately therefrom, as moisture-retaining tissue products, there are those which are obtained by supporting a moisture-retaining component such as glycerol on crepe-treated thin crepe papers. The moisture-retaining component absorbs moisture to thus put the crepe papers in an adequate moisture-retained condition, so that when being used those crepe papers feel moist and soft and have a pleasant texture and are easy to wipe such as dirt off.
In patent document 1 below, there is disclosed an art in which a chemical liquid containing such as a moisture-retaining agent, a softening agent, and an antioxidant is coated to a base paper to thereby enhance textures such as a moist feel and softness and provide a home-use tissue which prevents the skin from smarting or reddening even if being often brought into contact with the skin.
As to multiple-ply products (e.g. tissues such that two or more pieces of crepe paper are piled on each other, toilet paper such that one or more pieces of crepe paper is wound in a roll shape), it is requested that an air layer should be interposed between plies of the crepe paper so that they are abundant in a fluffy feel. Its reason is that this “fluffy feel” not only makes them feel pleasant such as when being used but also enhances use properties such as sweat absorption.
Thus, as to a crepe paper, there is carried out a method in which the bulkiness is produced by embossing a raw crepe paper. That is, an embossed crepe paper.
In patent document 2 below, there is proposed an art in which a crepe paper is provided with a high roll bulkiness and a high roll hardness by steaming the crepe paper and then embossing it.
In patent document 3 below, there is disclosed a paper tissue and its manufacturing technique, wherein the paper tissue comprises multiple ply (paper layer) and has a predetermined caliper (thickness) and a predetermined physiological surface smoothness parameter. As a specific example, there is disclosed a manufacturing example in which a paper tissue is obtained by coating an embossed three-ply tissue with a lotion. Therefrom it follows that both the embossment and the supporting of a moisture-retaining liquid are carried out.                [Patent Document 1] JP-A-2003-164385 (Kokai)        [Patent Document 2] JP-A-2002-511537 (Kohyo)        [Patent Document 3] JP-A-2003-514640 (Kohyo)        
The embossment in prior conventional tissue products was applied to a dry-conditioned raw crepe paper of which the paper-making and crepe treatment had been finished.
In the dry-conditioned raw crepe paper, fibers fixed to each other by hydrogen bonding are difficult to move each other. If such a raw crepe paper is embossed, then fibers do not smoothly move each other, so fibers themselves are broken or the hydrogen bonding between fibers are destroyed. As a result, the obtained embossed crepe paper is inferior in strength or tends to generate a paper dust.
There is known a crepe paper having the bonding between fibers reinforced with such as a paper strength agent in order to solve such problems. Since it has many bonded sites between fibers, there are advantages in that: deformation can be endured, the embossment can be comparatively well carried out, and the apparent density can be decreased. However, there is a tendency such that textures expressed by such as softness and a fluffy feel are deteriorated, so the commercial value as a tissue product is inferior.
In the method as described in patent document 2 above where steaming is carried out before the embossment, fibers are swollen with steam to thus become easy to deform, so that the embossment is easy to carry out. However, when drying after the embossment, the fibers tend to return to their unembossed shapes. There is also a demerit such that if water taken in the inside of the swollen fibers vaporizes, then the fibers, in other words, the embossed shapes, shrink, so that the embossed paper becomes hard.
There is also proposed an art in which the embossment is applied to an undried high-wet-conditioned raw crepe paper in the paper-making step. However, if the embossed raw crepe paper is dried by such as Yankee drier treatment, then its surface becomes smooth, so that embossed shapes disappear. If non-contact drying treatment with such as hot air is carried out, then the drying is possible without damaging the embossed shapes. However, it takes a long time and a large energy cost to dry the just made high-wet-conditioned raw crepe paper in the non-contact, so the economical performance is inferior. It is impossible to smooth the surface or equalize such as thickness by the Yankee drier treatment. The surface quality of the paper is deteriorated, or great dispersions in thickness and properties are made. In the paper-making step, sufficient hydrogen bonding is not formed between fibers, but fibers are in a condition of being free to become deformed and move each other, so it is difficult to clearly form fine embossed shapes. In the drying step, the embossed shapes tend to crumble, become deformed, or revert.
If, as described in patent document 3 above, an embossed paper material is coated with a moisture-retaining liquid, then such an embossed paper material cannot uniformly be coated with the moisture-retaining liquid. The embossed patterns crumble due to absorption of the moisture-retaining liquid. The functions of the embossment and of the moisture-retaining liquid cannot sufficiently be exercised.
It can also be considered post-embossing a moisture-retaining tissue manufactured by carrying out moisture-retaining treatment with a moisture-retaining liquid. However, on the moisture-retaining tissue softened by the moisture-retaining treatment, it is difficult to form embossed shapes by only carrying out conventional embossment. In addition, since the moisture-retaining treatment deteriorates the paper strength, damage tends to be done in the embossing step, so the embossment is difficult.